First, try unchecking Preferences > Performance > Use Graphics Processor. Assuming that doesn't help, then you may need to roll back your Nvidia driver: Image previews and thumbnails look tiled or broken on Windows
Thanks a lot. I did this and it's now working properly.
Just a question though, does it have an impact on performance (speed) ?
I did this and it's now working properly.
If you are referring to disabling the GPU, most people report it makes little difference unless you have a 4K or 5K display, in which case enabling the GPU can often speed up Develop operations noticeably. See here for more discussion: http://www.lightroomqueen.com/lightroom-performance-debunking-myths/
Make sure you've installed the most recent compatible graphics driver. If you update your driver to a newer version, you may be able to reenable the GPU: Adobe Lightroom GPU Troubleshooting and FAQ . But as that article notes, you'll need to go to the manufacturer's Web site to get the most recent drivers -- you can't rely on Windows update. (If you're on Mac, you just have to wait for whatever Apple decides to give you in its OS updates.)